1909.] The Life History of the Pacific Salmon. 35 



undoubtedly greatly exceeds the Canadian pack, probably reaching well 

 toward, if not exceeding 900,000 cases, so that the total Fraser River 

 Sockeye pack will fall but little below that of 1905 and will probably 

 exceed that of 1897. There are certain obvious objections to taking these 

 figures of the cannery pack at their face value as indications of the extent 

 of the run of fish in any year. The greater pack in certain years may, 

 for instance, be due to a greater number of canneries being in operation. 

 I have, however, plotted out the average pack per cannery for the same 

 period of sixteen years and the results are essentially the same as those 

 obtained by plotting the total pack. The averages, however, bring out 

 more clearly the periodicity in the years prior to 1 893 when the number of 

 canneries in operation was much smaller than in later years. Indeed, by 

 them the four year periodicity can be distinguished clearly as far back as 

 1885. Beyond that, however, a new feature is revealed, namely the oc- 

 currence of large runs in two of the years constituting a four year period. 

 This does not invalidate the conclusion as to the existence of the period ; 

 it merely indicates the probable occurrence of two good four year periods 

 in these early years instead of the single one which alone persists. I 

 shall have, however, occasion to return to this method of comparing the 

 runs later. 



It is worthy of note that this periodicity of the big runs is evident only 

 in the Fraser River. The runs in the Skeena and other northern rivers, 

 though varying materially in dift'erent years, do not show any definite 

 periodicity. What brought about the periodicity of the big runs in the 

 Fraser is entirely unknown. How long it has existed we do not know, 

 nor can we clearly picture the conditions, geological or climatic, that may 

 have produced an especially favourable year for the fish or three succeed- 

 ing unfavourable ones or a combination of both. But the facts presented 

 demonstrate the existence of the periodicity ; it is a fact so far as the Fraser 

 River Sockeye are concerned and not a theory. 



Granting then its occurrence what bearing has this four years period- 

 icity upon the life history of the salmon? Let us recall the fact that none 

 of the fish that reach the spawning grounds return to the sea; the runs 

 of future years must be composed solely of fish that are for the first time 

 ascending to the spawning grounds. Further, it is to be expected that in 

 the years of the big runs more fish will reach their normal destination and 

 therefore that there will be a greater number of eggs spawned than in the 

 poor years. That this expectation is fulfilled is shown by Commissioner 

 Babcock's observations of the spawning grounds in different years and he 

 produces concrete evidence* concerning it from the take of eggs by the 



*Report of the Fisheries Commissioner for British Columbia for the Year 1906. 



